Apparatus for heat-treating



Patented July 19, 1932 UNTED STATES PATENT oFFlcE PAUL L. GEER, OF BELLEVUE, PENNSYLVANIA, .ASSIGNOR T ATIICQ, INCORPORATED, 0F PITTSBURGH, PENNSYLVANIA, A CORFORATION PENNSYLVANIA APPARATUS FOR HEAT-TREATING Application filed December 23, 1927. Serial No. 242,132.

My present invention relates to the heattreating of metal and other articles wherein the articles are given successive heat-treatments in a plurality of heat chambers, fur naces or ovens.

Thus for instance in enameling metal articles, according to the present practice the article to be enameled is successively dipped, placed by hand in a drying oven and when dried is removed and placed in a burning furnace. After the first coat of enamel is baked, the article is removed, redipped, dried and again inserted into a burning furnace, and these steps of dipping, drying and burning are repeated-until the desired enameling is effected.

It is evident that such practice requires repeated manual handling of the product during the enameling process, resulting in high labor and fuel costs and much loss of time. Again, owing to the importance of the human factor the product is lacking in uniformity and quality. Moreover a relatively excessive amount of factory space is needed for the operation. l

The object which I have in view is the provision of an improved enameling apparatus which will minimize the import-ance of the human. factor, which will economize valtime required for completing theoperation, which will insure a product of high quality and of uniform character, and which will be attended by fuel economy. p

The apparatus which I have invented consists of a unit comprising a plurality of drying ovens and burning furnaces alternately I provide novel means for maintaining the desired temperatures in the drying ovens and in maintaining the necessary atmospheric dryness therein.

Other novel features will vappear from the following description.

In the accompanying drawing, wherein -I have illustrated the best embodiment of the Vprinciples of my invention now known f" to me, Fig. 1 is a plan view.; Fig. 2 isa side elevation, vand Fig. 3. is a longitudinal section on enlarged scale and taken along the Aline 3-3 in Fig. l.

Referring to the drawing, I provide a t 4continuous conveying floor which may be, as

shown, composed of the conveying rollers 1 which are power-rotated by any convenient means in a direction clockwise inFig. 3.

2 represents a drying oven through which the conveying ioor extends, the front end of .the conveying floor being exposed so that -the dipped articles may be placed thereon to rbe carried into and through the oven 2.

uable factory space, which will reduce the 3 represents a' burning furnace next in sequence to the drying oven 2 and through which the conveying ioor also extends. The coa-t of enamel which has' been dried in oven 2 is burned in furnace 3. -The burning fur- -nace is preferably of the munie-type, as

shown in Fig. 3. f

In the rear of the furnace 3 a sufficient portion of the conveying floor is exposed to permit the articles to be removed for redipping. The redipped articles are replaced on said exposed portion of the conveying floor.

1 Next in sequence is a second drying oven 2 in which the second coat of enamel is dried and through which the conveying floor extends. Next in sequence is a second burning furnace 3 wherein the second coat is burned and through which the conveying floor extends. In the drawing I have illustrated three pairs of drying ovens and burning furnaces placed end to end, thus providing for the drying and burning of three coats of enamel. In case additional coats are to be given to the product additional pairs of drying ovens and burning furnaces are provided to the desired number, the conveying floor extending continuously through the same.

The conveying floor is extended and eX- posed beyond the linal burning furnace to permit the removal of the finished articles.

The ends of the burning furnaces are provided With adjustable end doors 4 to regulate the burning temperatures and to permit the travel of the articles into and out of the furnaces along the conveying floor.

The drying ovens are preferably heated by the Waste gases from the burning furnaces.

The Waste `gases from the furnaces 3 are led to the recuperators 6 through the pipes 7 and air heated in said recuperators by said 'Waste gases is led from the recuperators through the pipe 8 and branch pipes 9 to the arcuate inverted U-.shaped chambers l0 mounted on the roof arches of the drying chambers, the lovv-er ends of said chambers 10 communicating With the interior of the drying ovens and the heated vair from the pipes 9 being admitted near one end of a chamber l0, thus causing an upward suction of the air from the drying oven and its circulation through the chamber 10 during which time it is dried and reheated by the air from the recuperator, so that when the air is returned into the interior of the oven at the other end of the chamber l0 it is restored to its original heat yand dryness. Thus I am able to maintain the uniform predetermined drying temperature in the vdrying chamber and to prevent the saturation or partial saturation of the atmosphere of the ovens by the moisture taken up from the enameling fluid.

This arrangement of air reheating and drying chambers connected to the interior of the drying oven and Which receive the heated air from the recuperators wher-ein the Waste gases from the burning furnaces are employed `for heating results in a very substantial economy in fuel.

It is evident that the use of my improved apparatus also accomplishes a very marked saving in labor costs and also in time. They also effect a substantial saving in plant space.

The product is also of a superior quality because of the diminution of the human factor.

What I desire to claim is:

l. In enameling apparatus, the combination of a drying oven, a burning furnace, said oven and ysaid furnace bein-g separated by an intervening open space, a continuous conveyer extending through said oven, said open space and said furnace, a recuperator receiving the Waste gases from the furnace, an air passage connected at two spaced apart points with the interior of the oven, and a Vchamber to the burning chamber.

preheated air connection between the recupcrator and said passage, the air being Withdrawn from the drying oven at one end of the passage and dried and then reintroduced into the drying oven at the other end of the passage.

A 2. In enameling apparatus, the combination of a drying oven, a burning furnace, said oven and said furnace being separated by an intervening open space, ya continuous conveyor extending through said oven, said open space and said furnace, a recuperator receiving the Waste gases from the furnace, an air passage connected at both ends to said oven, and a preheated air connection from the rec'uperator to said passage, :the air being Withdrawn from the drying oven at one end of the passage and dried andthen reintroduced into the drying oven at the other end of the passage.

3. In enameling apparatus, the combination of a drying oven, a burningfurnace, said oven and said furnace being separated by an intervening open space, a continuous conveyer extending through Vsaid `voven, said open space and said furnace, a recuperator receiving the Waste gases from the furnace, a U-shaped air passage connected at both ends to said passage, and means forA employing the preheated air 'from said recuperator to cause a circulation of the oven air through said passage, the air being Withdrawn from the drying'oven at one end of the passage and dried and then reintroduced into the drying u oven at the other end of the passage.

4. In heat treatment apparatus, the combination of a drying chamber and a burning chamber arranged in series, said chambers being spaced apart by an interposed open space, independent conveying means contained in each of said chambers, and means for conveying the product from the drying 5. In heat treatment apparatus, the combination of a plurality of pairs of chambers each comprising a drying chamber and a burning chamber, `said chambers being spaced apart by an interposed open space, said pairs being in alinement an-d in spaced relation with each other, means for conveying the product in turn through said pairs of chambers and means for conveying the products over the intervening spaces between the chambers.

6. In heat treatment apparatus, the combination of a plurality of pairs of chambers each comprising a drying chamber and a burning chamber, said pairs being in alinement and in spaced relation With each other, independent conveying means 'contained in V each of said chambers, and means for conveying the product from one pair of chambers to the neXt pair of chambers.

7 In heat treatment apparatus, the'cont bination of a pluralitybf pairs of chambers each comprising a drying chamber and a burning chamber, said chambers being spaced apart by interposed open spaces, and said pairs being in alinement and in spaced relation with each other, and a continuous conveyer floor extending through said chambers and said open spaces and comprising power driven rollers.

8. In heat treatment apparatus, the combination of a drying chamber and a burning chamber arranged in series, said chambers being spaced apart by an intervening open space, and a continuous conveyer floor extending through said chambers and said open space and comprising power driven rollers.

9. In enameling apparatus, the combination with a drying oven, a burning furnace, said drying oven and furnace being arranged for straight line operation, and a recuperator wherein air is heated by the waste gases from the furnace, of means for drying the atmosphere in the drying oven comprising means for withdrawing the air from said oven, heating said air and reintroducing said air into the oven.

10. In enameling apparatus, the combination with a drying oven, a burning furnace and a recuperator wherein air is heated by the waste gases from the furnace, of means for drying the atmosphere of said drying oven which consists of a passage having its ends connected to said furnace at points spaced longitudinally of the latter whereby a portion of the air may be by-passed through the passage, and a hot air inlet leading from the recuperator to said passage.

11. In enameling apparatus, the combination with al drying oven, a burning furnace and a recuperator wherein air is heated by the waste gases from the furnace, of means for drying the atmosphere of the drying oven which consists of a plurality of passages each having its ends connected to the drying oven at points spaced longitudinally of the drying oven whereby a portion of the air may be by-passed through the passage, and hot air inlets leading from the recuperator to said passages.

12. In heat-treatment apparatus, the combination of a heating chamber, an air circulating passage having an inlet portion and an outlet portion, both portions connected to said chamber, and means for causing circulation of the air of said chamber through said passage whereby to create regulable air currents in said chamber.

13. In heat-treatment apparatus, the combination of a heating chamber, an air circulating passage having an inlet portion and an outlet portion, both portions connected to said chamber, means for causing circulation of the air of said chamber through said passage whereby to create regulable air currents in said chamber, and means for reheating the air traveling through said passage.

14. In heat-treatment apparatus, the combination of a heating chamber, a plurality of air circulating passages each provided with an inlet portion and an outlet portion,

both portions being connected to said chamr ber, and means for causing air from said chamber to circulate through said passages whereby to create regulable air currents in said chamber.v

15. In heat-treatment apparatus, the combination of a heating chamber, a plurality of air circulating passages each provided with an inlet portion and an outlet portion, both portions being connected to said chamber, means for causing air from said chamber to circulate through said passages whereby to create regulable air currents in said chamber. and means for reheating the air traveling through said passages.

16. In heat-treatment apparatus, the combination of a heating chamber, means for causing the product to be treated to travel through said chamber, a plurality of aircirculating passages having their inlet and outlet ends connected to said chamber, and means comprising the introduction ofl heated air into said passages for causing a circulation of currents of air within said chamber and through said passages.

17. In heattreatment apparatus, Vthe combination of a heating chamber, means for causing the product to be treated to travel through said chamber, a plurality of aircirculating passages having their inl-et and outlet ends connected to said chamber, said passages being positioned in spaced relation to each other longitudinally of said chamber, and means comprising the introduction of heated air into said passages whereby circulating currents of heated air are set up throughout said chamber whereby to mainain the desired heat exchange in said cham- Signed at Pittsburgh, Pa., this 21st day of December, 1927.

' PAUL L. GEER. 

